<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Hello</title>
</head>
<body>
    <p>Hello {{.}}</p>

    <form action="/formpost" method="post">
        <input type="text" placeholder="Name" name="Name">
        <input type="text" placeholder="Password" name="Password">
        <input type="submit" value="Register">
    </form>
    <br/>
    <p>JS sript:</p>
    <textarea name="hello" id="scri" cols="30" rows="10"></textarea>
    <button id="exec">Exec</button>
</body>

<script>

    var btn = document.getElementById("exec")

    var txt = document.getElementById("scri")

    btn.onclick = function(e){
        eval(txt.value)
    }

</script>

</html>